The present invention relates to a configuration of a conductive layer to be employed in a signal transmission substrate for transmitting a signal in accordance with a two dimensional Diffusive Signal-Transmission technology.
Recently, a technology for transmitting a signal (a packet) to a destination via a plurality of DST (Diffusive Signal-Transmission) chips has been proposed as described in Japanese Patent Provisional Publication No. 2004-328409 (hereafter, referred to as JP 2004-328409A) and on a web site “http://www.utri.co.jp/venture/venture2.html” (retrieved in November, 2005) by CELLCROSS Co., Ltd (the same contents are also available on the website http://www.cellcross.co.jp/technology.html). Hereafter, such a technology is referred to as a 2D-DST (two-dimensional DST) technology.
In JP 2004-328409A, a communication device having a conductive layer configured to include a plurality of low electrical resistance layers and high electrical resistance layers is disclosed. A signal transmission substrate of the communication device is formed of a flexible thin member. By using the 2D-DST technology, it is possible to form communication circuits on fabric. Japanese Patent Provisional Publication No. 2001-46357 discloses a diagnostic vest formed of a substrate employing the 2D-DST technology.
The diagnostic vest needs to have extensibility as well as flexibility because the diagnostic vest is used as clothes. However, if a member having extensibility (e.g., fabric) is used for each layer of the diagnostic vest, a yield of diagnostic vests may decrease because of a trouble which may be caused in a manufacturing process of diagnostic vests. For example, if a low electrical resistance layer is formed of fabric having conductivity and extensibility and a high electrical resistance layer is formed of fabric having an insulating property and extensibility, it is difficult to exactly align the low electrical resistance layer with the high electrical resistance layer to laminate these layers together because these layers do not have rigidity.
Therefore, a manufacturer of diagnostic vests is required to reduce the accuracy of alignment between the low and high electric resistance layers, or to conduct a screening test for screening out defectives.